Pulmonary Embolus – A Great Two Part Course From Emergency Medicine Cases

This blog is my peripheral brain. Before smart phones and tablets, most doctors carried a pocket reference of his or her specialty [The Washington Manual for Internal Medicine, The Harriet Lane Handbook for Pediatrics, etc]. Now, this blog is my peripheral brain since I always have my smart phone in my pocket.

These two podcasts and show notes on Pulmonary Embolus from Emergency Medicine Cases, #113 and #114, are truly awesome. Together the two parts comprise an expert course on Pulmonary Embolus. I have not included any excerpts of the show notes for either podcast as the show notes are incredibly good – you need to review everything in both of them [Note to myself].

This is EM Cases Episode 113 Pulmonary Embolism Challenges in Diagnosis Part 1.

If we were to design a perfect emergency medicine brain buster, it would have all the qualities of pulmonary embolism. It would affect the young and the old. It would be precipitated by seemingly anything: medications, smoking, and even video gaming. It would be dynamic, anything from asymptomatic to killing in minutes. It would have a huge variability in presenting signs and symptoms depending on a whole host of patient factors. It would have multiple decision rules, imaging modalities, and treatment options. It’s as if pulmonary embolism was invented just to challenge the minds of ED docs! In this two part podcast, with the help of thrombosis experts Dr. Kerstin DeWit and Dr. Eddy Lang, we ask the questions that plague us on almost every shift: Which patients require any work-up at all for pulmonary embolism? What’s the utility of PERC and Wells scores? Should the newer YEARS decision tool supplant Wells? When should we order a D-dimer? What is the diagnostic role of CXR, ECG, POCUS, CTA and VQ? How should we work up pregnant patients for pulmonary embolism? How can we use shared decision making strategies for pulmonary embolism to help us do what’s best for our patients, and many more…

Suggested diagnostic decision tool algorithm for pulmonary embolism.

There are a number of decision rules that are used as objective aids in the work up of PE. Wells and PERC (Pulmonary Embolism Rule out Criteria) are the two most commonly utilized tools in North American EDs. It is important to understand how the prevalence of PE in your population impacts decision making. Simply put, the prevalence of a disease can be considered the pre-test probability of the patient ruling in for that disease. The maximum suggested prevalence for PE in order to use the PERC rule is 7%. In other words, if there is a high prevalence of PE in your population, PERC may not be applicable.

The PROPER trial out of France, where the prevalence of PE is low, showed that gestalt performed similarly to PERC in terms of 3-month PE rate, but PERC resulted in an 8% decrease in unnecessary CT scanning, and a 40-minute decrease in ED stay [11]. While studies have suggested that physician gestalt may be as accurate as these decision tools [11,12], there is an argument to be made that even seasoned docs should take the time to calculate these scores because even they can have a tendency to overestimate pretest probability at times.

An Algorithmic Approach

Once you have decided to test for PE, our experts suggest starting with Wells to get an idea of the pre-test probability.

In Part 1 of Pulmonary Embolism Challenges in Diagnosis Drs. Helman, Lang and DeWit discussed a workup algorithm using PERC and Wells score, the bleeding risk of treated pulmonary embolism, pearls in decision making on whether or not to work up a patient for pulmonary embolism, how risk factors contribute to pretest probability, the YEARS criteria and age-adjusted D-dimer. In this Part 2 we answer questions such as: what are the important test characteristics of CTPA we need to understand? Which patients with subsegmental pulmonary embolism should we treat? When should we consider VQ SPECT? What is the best algorithm for the work up of pulmonary embolism in pregnant patients? How best should we implement pulmonary embolism diagnostic decision tools in your ED? and many more…